Although clinical epidemiological studies suggest that stx2 is more often associated with severe disease and development of hemolytic–uremic syndrome (HUS) than stx1, pointing out for a high pathogenicity of the isolated STECs, the stx2 subtype found in this study was always stx2b, a subtype with a potency similar to that of stx1 [68]. This evidence concerns the gene STX1A and hemolytic-uremic syndrome.